[PULL 40/56] hw/sparc/leon3: check cpu_id in the tiny bootloader

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

From: Clément Chigot <chigot@adacore.com>

Now that SMP is possible, the asr17 must be checked in the little boot
code or the secondary CPU will reinitialize the Timer and the Uart.

Co-developed-by: Frederic Konrad <konrad.frederic@yahoo.fr>
Signed-off-by: Clément Chigot <chigot@adacore.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20240131085047.18458-9-chigot@adacore.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 hw/sparc/leon3.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/hw/sparc/leon3.c b/hw/sparc/leon3.c
index 1637900162..bea84f3ad6 100644
--- a/hw/sparc/leon3.c
+++ b/hw/sparc/leon3.c
@@ -99,12 +99,26 @@ static uint32_t *gen_store_u32(uint32_t *code, hwaddr addr, uint32_t val)
 
 /*
  * When loading a kernel in RAM the machine is expected to be in a different
- * state (eg: initialized by the bootloader). This little code reproduces
- * this behavior.
+ * state (eg: initialized by the bootloader).  This little code reproduces
+ * this behavior.  Also this code can be executed by the secondary cpus as
+ * well since it looks at the %asr17 register before doing any
+ * initialization, it allows to use the same reset address for all the
+ * cpus.
  */
 static void write_bootloader(void *ptr, hwaddr kernel_addr)
 {
     uint32_t *p = ptr;
+    uint32_t *sec_cpu_branch_p = NULL;
+
+    /* If we are running on a secondary CPU, jump directly to the kernel.  */
+
+    stl_p(p++, 0x85444000); /* rd %asr17, %g2      */
+    stl_p(p++, 0x8530a01c); /* srl  %g2, 0x1c, %g2 */
+    stl_p(p++, 0x80908000); /* tst  %g2            */
+    /* Filled below.  */
+    sec_cpu_branch_p = p;
+    stl_p(p++, 0x0BADC0DE); /* bne xxx             */
+    stl_p(p++, 0x01000000); /* nop */
 
     /* Initialize the UARTs                                        */
     /* *UART_CONTROL = UART_RECEIVE_ENABLE | UART_TRANSMIT_ENABLE; */
@@ -118,6 +132,10 @@ static void write_bootloader(void *ptr, hwaddr kernel_addr)
     /* *GPTIMER0_CONFIG = GPTIMER_ENABLE | GPTIMER_RESTART;        */
     p = gen_store_u32(p, 0x80000318, 3);
 
+    /* Now, the relative branch above can be computed.  */
+    stl_p(sec_cpu_branch_p, 0x12800000
+          + (p - sec_cpu_branch_p));
+
     /* JUMP to the entry point                                     */
     stl_p(p++, 0x82100000); /* mov %g0, %g1 */
     stl_p(p++, 0x03000000 + extract32(kernel_addr, 10, 22));
-- 
2.41.0